1. Field of the Invention
Embodiments disclosed herein generally relate to a magnetic read head for use in a hard disk drive.
2. Description of the Related Art
The heart of a computer is a magnetic disk drive which typically includes a rotating magnetic disk, a slider that has read and write heads, a suspension arm above the rotating disk and an actuator arm that swings the suspension arm to place the read and/or write heads over selected circular tracks on the rotating disk. The suspension arm biases the slider towards the surface of the disk when the disk is not rotating but, when the disk rotates, air is swirled by the rotating disk adjacent an air bearing surface (ABS) of the slider causing the slider to ride on an air bearing a slight distance from the surface of the rotating disk. When the slider rides on the air bearing, the write and read heads are employed for writing magnetic transitions corresponding to host data. The read and write heads are connected to a signal processing circuitry that operates according to a computer program to implement the writing and reading functions.
As areal densities increase, the dimensions of both bits and the read back sensor must become smaller and smaller. For readers designed with a spin valve structure, such as all GMR, TMR and CPP-GMR readers, the increasingly smaller free layer will show more thermal fluxuations resulting in greater noise in the device. The greater noise will reduce SNR to below acceptable limits for magnetic recording above 1-2 Tb/in2. Spin Torque Oscillators (STO) are being investigated which may be less sensitive to thermal fluxuations. Instead of detecting bits by the resistance change resulting from rotation of the free layer in response to the media field, this new device uses the change in frequency of spin torque induced precession of the magnetizations of a magnetic layer that is caused by changes in the field from the disk.
Therefore, there is a need in the art for an improved read head.